The present invention relates to electrical machines and, more particularly, to a cross-shaped rotor for a rotating electrical machine, such as a generator, including fins that increase the section bending moment of inertia about an axis.
In a conventional generator having a rotor and a stator, the rotor is provided with field windings that excite the generator while receiving a current from an exciting current source. The stator is provided with armature windings which supply electrical power output.
Conventional generator rotors use cross-slots to equalize the bending stiffness between direct (D) and quadrature (Q) axes. With newer generators using a modular winding assembled over a solid rotor with parallel sides, dissymmetry of the bending stiffness is aggravated and effective winding support and position become significant challenges.
In an exemplary embodiment of the invention, a generator rotor includes pole faces arranged at locations on a direct axis and fins arranged along a quadrature axis such that the rotor is cross-shaped. The direct and quadrature axes are each normal to the rotor axis of rotation. The fins act to increase a section bending moment of inertia about the direct axis and provide winding position reference and bases of winding support. In one embodiment, the rotor includes two pole faces situated on the direct axis at either side of the quadrature axis, respectively. The fins may be formed integral with the rotor, such as by machining, forging welding, or casting. Alternatively, the fins may be mechanically secured to the rotor.
In another exemplary embodiment of the invention, an electric generator includes a rotor provided with field windings and a stator provided with armature windings which supply electrical power output. The rotor comprises pole faces arranged at locations on a direct axis and fins arranged along a quadrature axis such that the rotor is cross-shaped.